Many semiconductor devices generate heat which, if not dissipated, can raise the temperature of the device sufficiently to damage it causing abnormal operation or complete failure. Therefore, it is common practice to attach the semiconductor device to some form of a heat dissipator, commonly known as a heat sink, which functions to absorb heat from the device and transfers the heat to the surrounding atmosphere.
Typically, a semiconductor device is furnished with a heat transmitting surface which can be attached by a mechanical fastener, such as a machine screw, to some form of a heat dissipator. The assembled semiconductor device and heat dissipator are then attached to a support, such as a printed circuit board, where the electrical leads emanating from the semiconductor device are attached, usually by soldering, to connection pads located on the printed circuit board. A mechanical fastener, such as a screw, is commonly used to attach the heat transmitting surface to the heat dissipator and has the advantage in that sufficient contact pressure can be created between the heat transmitting surface of the semiconductor device and the heat dissipator for good heat conduction therebetween. Disadvantages of using a mechanical fastener, such as a screw, includes both the cost of the screw, the time consuming assembly procedure required and the tight geometric tolerance that must be maintained if several devices are to be mounted in sequence.
For these reasons, heat dissipators have been suggested which resiliently grip the semiconductor device such as those disclosed in U.S. Pat. Nos. 4,509,839, 5,065,279, 4,933,746, 5,019,942, and 4,462,462 the disclosures of which are hereby incorporated by reference. These techniques eliminate the need for mechanical fasteners, such as screws, which require accurate alignment and time consuming assembly methods. However, each of these heat dissipators and the method used to secure the semiconductor device thereto is encumbered by one or more disadvantages which makes it less than ideal for its intended purpose. For example, heat dissipators illustrated and described in U.S. Pat. Nos. 4,012,769; 4,215,361; and 4,235,285 each resiliently grips the semiconductor device. However, none of these heat dissipators provide means for attaching the heat dissipator to a support such as a printed circuit board. U.S. Pat. No. 4,509,839 discloses a heat dissipator to which a semiconductor device is secured by means of a resilient clip. However, no provisions are disclosed for attachment of the heat dissipator to a printed circuit board and attachment of the electrical leads from the semiconductor device to the printed circuit board often cause failure from mechanically induced stress. Also, since the semiconductor must be electrically insulated from the heat dissipator, the bolt used to attach the semiconductor mounting tab must be insulated. This usually involves a time consuming assembly operation with tight tolerances and tedious methods due to a large number of components.